ETL 1110-2-544
31 Jul 95
stability of the foundation, as determined by a slope
stability analysis.
(2) Stability of the levee. The stability of the
levee implied by the displacements is consistent with
the safety factor computed by the limit-equilibrium
method. This is shown in Figure 15 where the sheet-
pile wall movements are sensitive to safety factors less
than about 1.3.
Figure 13. Computed and measured deflections of
sheet-pile wall
Figure 15. Displacement computed by the finite
element method versus factor of safety computed
by limit equilibrium method
(3) Increased pile penetration. Increased pile
penetration does not improve the stability of the
levee.
Figure 14. Computed and measured bending
moments in sheet-pile wall
(4) Pile stiffness. Pile stiffness has little effect on
the total displacements.
h. Results of the parametric analysis. The
parameter study was designed to evaluate the effects of
(5) Deflection of sheet-pile wall. Deflection of
pile embedment depth, soil strength, and pile type on
the sheet-pile wall, as determined with conventional
the performance of the system at various water levels.
design programs, is a poor criterion for design of
The finite element analyses were performed in
sheet-pile walls because movements are caused by
conjunction with a limit equilibrium analysis to
shear deformations in the foundation and not the
establish a link between the displacements computed
cantilever action of the pile.
with the FEM and the safety factor computed with the
limit equilibrium method. Some of the key findings of
Based on the findings of the parametric analysis,
the parametric analysis include:
Leavell et al. (1989) were able to successfully develop
a design procedure based on the finite element for
(1) Deep-seated movements. Deep-seated
sheet-pile design. The procedure gives designers
movements in the levee foundation controlled the
charts for making a "correction" to the displacements
magnitude of sheet-pile deflection, particularly in soft
computed with the conventional design programs.
soils. As a result, the height of water loading that can
This correction accounts for the effect of the deep-
be sustained by a particular wall is controlled by the
seated movements on the pile deflections.
A-14
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